We have already conducted local therapy by slowly releasing anticancer composite to malignant brain tumors. We administed either ACNU pellet or 5Fu pellet at the time of the operation or under CT guided in treating of 81 cases of malignant brain tumor. From 1 to 10 pellets containing 10 mg-20 mg of ACNU of from 1-6 pellets containing 5 mg-20 mg of 5Fu were administered. In ACNU cases, the response of the tumor tissue to local therapy was not so strong and no peripheral edemas was observed on CT scan. In the 5Fu pellets cases, a severe brain edema was seen in and around the pellet from the 7th to 21st days after implantation of pellet. This edema gradually improved and showed low density only around the lesion. It is thought that this is due to the occurence of leucoencephalopathy of cause of 5Fu. Sufficient histological studies have not yet been carried out. But in one case who was reoperation on the 10th day after pellet implantation, histological examination revealed marked tissue necrosis and no remaining tumor cells were seen. Thus the tissue response to 5Fu is extremely strong. 5Fu-pellet shows a stronger cytotoxic effect and greater degree of tissue infiltration than ACNU. Copolymers of lactic acid and valerolactone with a number-average molecular weight of 1500-2600 were developed as biodegradable carriers for drug delivery. When CDDP-lactone polymer was implanted in the brain of rat, histologically, the brain tissue is markedly changed. The area of necrosis and response of connective tissue were seen around the implantation site from 5th day to 20th days.
